(WEST LAFAYETTE) - Officials at Purdue University are urging Indiana campers to be careful with their firewood this summer to help prevent the spread of the emerald ash borer.

Entomologist Annemarie Nagle says a state Department of Natural Resources rule requires Indiana firewood to be accompanied by a state or federal compliance agreement, be kiln-dried scrap lumber, or be completely debarked. Firewood brought from another state without a federal compliance agreement is illegal.

Nagle urges campers to buy firewood close to where they will burn it and to burn it completely before they leave.

A quarantine outlawing movement of any ash wood out of its boundaries has been expanded to include all but 13 of Indiana's 92 counties.